Our long term objective is to locate the brain stem neurons which generate the respiratory pattern in the cat. We intend to apply power spectral analysis to respiratory motor nerves and brain stem neurons. We will determine if a specific spectral peak in the inspiratory motor outputs is linked with a specific class of respiratory neurons in either the dorsal respiratory group of the ventrolateral nucleus of the tractus solitarius or the ventral respiratory group of the nuclei ambiguous and retroambigualis. Using focal cooling and heating, we will determine whether the high frequency synchrony of the inspiratory activity is a local or global property of the respiratory neuronal network. With these studies we hope to locate areas in the medulla and pons to explore with microelectrodes for neurons of the central respiratory pattern generator.